The invention relates to a web laying machine which is used to form superimposed layers of cloth to a given size or length on a laying table so that a plurality of sheets of cloth may be formed in one operation when cutting a stock material to a given pattern and size.
Several modes of laying a stock material are illustrated in FIG. 1. Specifically, FIG. 1A illustrates a laying operation in a zigzag-folded mode, FIG. 1B a laying operation in a simple mode in which the cloth is laid out in one direction, and FIG. 1C a laying operation in a face-to-face mode wherein a pair of adjacent superimposed layers have their front surfaces P facing toward each other and which thus is advantageous to cut a cloth into left and right portions of slacks according to a single paper pattern.
FIGS. 2A and 2B show one exemplary web laying machine of the prior art schematically, in a perspective view (FIG. 2A) and in a side elevation (FIG. 2B), partly broken away to show the section. The machine includes a laying unit 2 including a pair of sideplates 2' which are disposed in opposing relationship with each other and spaced apart by a given distance. Running wheels 3, 3' are mounted on the opposite sideplates toward their lower ends and engage a pair of rails 4, 4', respectively, which are disposed along the opposite lateral edges of a laying table 1. These wheels are adapted to be driven for rotation by an electric motor, not shown. The unit carries cutting means 5 on its front end, and also carries a pivotable casing 6 on its top which receives a stock material and which is rotatable about a vertical axis.
A horizontal base 7 extends across the pair of sideplates 2, 2', and includes a guide casing 7a which is channel-shaped in cross section, and a slide 7b which is slidable along the guide casing. The pivotable casing is mounted on and is supported by the horizontal base. The guide casing fixedly carries a pair of guide rails 8, 8' which are disposed on the front and the rear wall of the guide casing, respectively. A pair of brackets 9, 9' are mounted on the slide 7b toward the front and rear ends thereof and each carry rollers which are disposed to hold an associated one of the guide rails therebetween for achieving a smooth sliding movement.
A pivot shaft 10 has its lower end fixedly mounted on the slide 7b and has its upper end extending into the pivotable casing where a bevel gear 11 is mounted thereon. A thrust bearing 12 is interposed between the pivotable casing and the slide 7b in surrounding relationship with the pivot shaft 10. A pivotting motor 13 is secured within the pivotable casing and has an output shaft on which a bevel gear 14 is fixedly mounted and is in meshing engagement with the bevel gear 11 on the pivot shaft. A roll of stock material 16 is received on a pair of support arms 15, 15' mounted on a support shaft 17 which can be rotated to a given angular position in response to a drive from a motor 18. A transfer roll 19 is adapted to be driven by drive means, not shown, and is urged into contact with the roll 16 suspended across the support arms 15, 15', thus allowing a cloth 20 to be paid off the roll 16.
FIGS. 3A, B and C illustrate a laying operation in the face-to-face mode. The pivotable casing 6 is rotated through 180.degree. for each reciprocating movement of the laying unit. In these Figures, numerals 21 and 22 represent conveyor belts which are disposed within the laying unit for conveying a cloth paid off from the roll. It will be seen that a tension regulating plate 23 is disposed along the path of movement of the cloth.
As will be seen, the pivotable casing 6 is rotated in response to a drive from the pivotting motor 13 which is transmitted through the output shaft 10 thereof and the bevel gears 14, 11. It will be noted that since the roll of stock material 16 is placed on the support arms 15, 15', a torque of an increased magnitude is required during the initial phase of the laying operation for its rotation. On the other hand, a force of inertia resulting from weights of the roll 16 and other components has a great influence upon the pivotable casing 6 and the slide 7b toward the end of the rotation of the pivotable casing, causing a distortion of the support arms or other members or causing an offset in the position where the cloth begins to be paid off during a next cycle.
In the above description, it is assumed that the pivotable casing 6 is rotated through the engagement between the bevel gears which are mounted on the output shaft of the pivotting motor 13 which is secured to the casing and on the upper end of the vertical shaft which is stationary. However, alternatively, an annular gear may be secured to the slide 7b in surrounding relationship with the thrust bearing 12 and may be engaged by a suitable gearing which is coupled to the pivotting motor secured to the pivotable casing. Such arrangement may be reversed, namely, an annular gear may be mounted on the lower side of the pivotable casing while a pivotting motor may be secured to the slide 7b, in either instance, the problems mentioned above relating to the distortion of the support arms or other members or an offset in the position at the beginning of the pay-off operation cannot be avoided.
Such problems can be alleviated by rotating the pivotting motor 13 at a very low speed of rotation, but this substantially degrades the production efficiency. While the rotation of the pivotting motor may be controlled in a stepwise manner during the full rotation thereof, this requires a complex control mechanism, resulting in an increased cost. While an electrical control may be contemplated, fluctuations in the voltage may give rise to an error. In addition, it should be noted that the roll of stock material 16 placed on the support arms 15, 15' has a weight which varies from as low as 8 kg to as high as 100 kg. Such weight continuously changes in the course of paying the cloth off the roll 16 in a gradual manner, whereby a high level of technology is required.
The invention intends to overcome the described problems. Specifically, while the pivotting motor is caused to rotate at a uniform rate, an arrangement is made such that the rotation of the pivotable casing takes place slowly during the initial phase, at an increased rate during intermediate positions thereof and again slowly toward the end of rotation, thus achieving an efficient operation. In addition, mechanical means is employed to achieve such a speed control which assures a smooth and accurate operation while avoiding shocks and while maintaining its manufacturing cost at a low value.
Above and other objects, features and advantages of the invention will become apparent from the following description with reference to the drawings which illustrate one embodiment of the invention.